Gemini 3.8 Live is ahead on success rate, agent responses, data accuracy, stalled calls and response time, and GPT Realtime 2.1 Mini on reliability and interruption.
Last updated Methodology by Dileep Chagam
Pick Gemini 3.8 Live for calls that pass every check (7.7 points higher), getting the agent's replies right (0.8 points higher), saving the caller's data correctly (5.9 points higher), fewer stalled calls (0.4 points lower) and fast replies (0.17s sooner). Pick GPT Realtime 2.1 Mini for reliability across repeated calls (8.5 points higher) and handling interruptions (0.01 higher).
Scenarios that passed on all three runs.
Realtime 2.1 Mini, 8.5 points higher
Calls that passed every check.
Gemini 3.8 Live, 7.7 points higher
Calls where the agent's replies reached the expected outcome.
Gemini 3.8 Live, 0.8 points higher
Calls where everything the agent saved matched exactly.
Gemini 3.8 Live, 5.9 points higher
Calls where the agent went silent for 10 seconds or more.
Gemini 3.8 Live, 0.4 points lower
How well it handled being talked over, 0 to 5.
Realtime 2.1 Mini, 0.01 higher
Median time to start replying after the caller finishes.
Gemini 3.8 Live, 0.17s sooner
One minute of call at the vendor's published rates.
Not comparable
The small figure is the place among ranked models. The cascade is not ranked.
Gemini 3.8 Live 1.91s, Realtime 2.1 Mini 2.08s at the median.
Both providers, every model: Google vs OpenAI
GPT Realtime 2.1 Mini is more reliable, by 8.5 points. Gemini 3.8 Live passed 34 of 82 scenarios on all three runs, and GPT Realtime 2.1 Mini passed 41. A scenario only counts when every run of it passed.
For a phone agent, GPT Realtime 2.1 Mini, since it gets more scenarios right on every run. Gemini 3.8 Live is ahead on success rate, agent responses, data accuracy, stalled calls and response time, and GPT Realtime 2.1 Mini on reliability and interruption.
Gemini 3.8 Live, by 5.9 points. Gemini 3.8 Live saved everything exactly right on 70.5% of the calls that save data, and GPT Realtime 2.1 Mini on 64.5%. On Appointments, 78.4% against 88.8%. On Medicare, 50.0% against 0.0%. A call counts only when nothing is missing, wrong, extra or saved twice.
Yes. Gemini 3.8 Live starts replying 0.17s sooner at the median. Gemini 3.8 Live takes 1.91s at the median and 2.23s at p90; GPT Realtime 2.1 Mini takes 2.08s and 2.75s. Both are measured on the call audio, from the caller finishing to the agent starting to reply.
GPT Realtime 2.1 Mini, by 0.01 on a 0 to 5 scale. Gemini 3.8 Live scores 4.98 and GPT Realtime 2.1 Mini 4.99 for how well the agent handled being talked over.
Gemini 3.8 Live, by 0.4 points. The agent went silent for 10 seconds or more on 2.0% of Gemini 3.8 Live calls and 2.5% of GPT Realtime 2.1 Mini calls.
There is no verified per-minute rate for Gemini 3.8 Live, so cost cannot be compared yet.
Cekura ran both as the whole agent in the same open-source Pipecat pipeline, with the same prompt, tools and connection. A simulated caller worked through all 82 scenarios on live calls, three times each, 2,952 calls across the benchmark. A call passes only when the agent said the right things and saved the right data.
